Tiny arm bone unlocks mystery of Indonesia's extinct 'Hobbit' people
By Will Dunham
Aug 6 (Reuters) -When researchers excavated fossilized fragments of a rod-shaped bone 3-1/2 inches (88 mm) long at a site called Mata Menge on Indonesia's Flores island, the pieces initially were bagged and marked "crocodile bone fragment?" It was only later that they realized what they actually were.
These fragments, dating to about 700,000 years ago, of the upper arm bone, called the humerus, comprise the smallest limb bone known for any member of the human evolutionary lineage - an adult individual of the diminutive extinct species Homo floresiensis. And the fossil has unlocked the mystery of the origin of this species, nicknamed "The Hobbit."
Scientists on Tuesday announced the discovery of this incomplete humerus - missing both of its ends - as well as two fossilized teeth from Mata Menge in the So'a Basin of Flores, where the volcano Ebulobo looms over the landscape. While dental and jaw fossils of the same age previously were found at the site, the humerus is the first Hobbit bone beyond the cranium identified at Mata Menge.
Based on the bone's size, the researchers concluded the individual stood about 3 feet 3 inches (one meter) tall - about three inches (6 cm) shorter than the estimated height of the famous 60,000-year-old Homo floresiensis fossil uncovered in 2003 at the Liang Bua cave site roughly 50 miles (75 km) away.
Since the sensational discovery of Homo floresiensis, scientists have debated its origins. The leading hypotheses were that the Hobbit descended either from an archaic human species called Homo erectus, which arose in Africa and spread to other parts of the world, or from even more primitive species such as Homo habilis or Australopithecus afarensis, not known to have left Africa.
The similarities between the Mata Menge fossils and Homo erectus fossils from Indonesia's island of Java provide strong evidence that Homo floresiensis descended from that species, the researchers said.
"This means that Homo floresiensis experienced dramatic body size reduction from large-bodied Homo erectus, whose body size was similar to us modern humans," said University of Tokyo paleoanthropology professor Yousuke Kaifu, lead author of the study published in the journal Nature Communications.
The Flores fossils are most similar to Homo erectus fossils dating from 1.1 million to 800,000 years ago from Sangiran, Java, Kaifu said, and not the more primitive species.
"The discovery offers support to the idea that an evolutionary process known as island dwarfism tinkered with the genetics of a group of large-bodied Homo erectus that somehow made it from the continental landmass of Asia to the isolated island of Flores, perhaps one million years ago or more," said archaeology professor and study co-author Adam Brumm of Griffith University's Australian Research Centre for Human Evolution.
They reduced drastically in body size on Flores between about one million and 700,000 years ago, giving rise to Homo floresiensis, Brumm added.
Under the island effect, larger-bodied mammals such as elephants - which also resided on Flores - diminish in size over time.
"It is thought that the main reason for this size reduction over many generations is that being small has more advantages than being large on an island. Periodic shortages of food are most likely the main selective force toward smaller body size," said University of Wollongong paleontology professor and study co-author Gerrit van den Bergh.
Homo erectus first appeared roughly 1.9 million years ago, possessing body proportions similar to our own, though with a smaller brain.
The original length of the Mata Menge humerus, dug up in 2013 and properly identified in 2015, would have been about 7.9-8.3 inches (200-211 mm). That compares to the 9.6 inches (243 mm) for the later Liang Bua Hobbit and to an average of about 11.8 inches (299 mm) for modern-day people.
"I first thought that the tiny humerus could be a child," Kaifu said.
A microscopic examination of a sample of the Mata Menge humerus revealed evidence of a process called bone remodeling, showing it came from an adult.
Ten Homo floresiensis fossils, including some described in 2016, from at least four individuals - two adults and two children - have been excavated from sandstone at Mata Menge, along with stone tools. The fossils suggest that these Homo floresiensis progenitors were even slighter smaller than the later Hobbits.
Homo floresiensis went extinct not long after our species arrived in the region.
"I think our species very likely was the culprit," Brumm said. "This isolated lineage of archaic hominins seems to have existed on Flores for an extremely long time, and then it disappears not long after Homo sapiens is known to have established a presence in the region. That hardly seems a coincidence."
World's oldest cave painting in Indonesia shows a pig and people nL1N3IS02J
Study brings lifestyle of enigmatic extinct humans into focus nL1N3IS02I
Fossil of child with Down syndrome hints at Neanderthal compassion nL1N3IM0PD
Where did Homo sapiens go after leaving Africa? New study has an answer nL2N3G109R
Reporting by Will Dunham, Editing by Rosalba O'Brien
Ultime news
Disclaimer: le entità di XM Group forniscono servizi di sola esecuzione e accesso al nostro servizio di trading online, che permette all'individuo di visualizzare e/o utilizzare i contenuti disponibili sul sito o attraverso di esso; non ha il proposito di modificare o espandere le proprie funzioni, né le modifica o espande. L'accesso e l'utilizzo sono sempre soggetti a: (i) Termini e condizioni; (ii) Avvertenza sui rischi e (iii) Disclaimer completo. Tali contenuti sono perciò forniti a scopo puramente informativo. Nello specifico, ti preghiamo di considerare che i contenuti del nostro servizio di trading online non rappresentano un sollecito né un'offerta ad operare sui mercati finanziari. Il trading su qualsiasi mercato finanziario comporta un notevole livello di rischio per il tuo capitale.
Tutto il materiale pubblicato sul nostro servizio di trading online è unicamente a scopo educativo e informativo, e non contiene (e non dovrebbe essere considerato come contenente) consigli e raccomandazioni di carattere finanziario, di trading o fiscale, né informazioni riguardanti i nostri prezzi di trading, offerte o solleciti riguardanti transazioni che possano coinvolgere strumenti finanziari, oppure promozioni finanziarie da te non richieste.
Tutti i contenuti di terze parti, oltre ai contenuti offerti da XM, siano essi opinioni, news, ricerca, analisi, prezzi, altre informazioni o link a siti di terzi presenti su questo sito, sono forniti "così com'è", e vanno considerati come commenti generali sui mercati; per questo motivo, non possono essere visti come consigli di investimento. Dato che tutti i contenuti sono intesi come ricerche di investimento, devi considerare e accettare che non sono stati preparati né creati seguendo i requisiti normativi pensati per promuovere l'indipendenza delle ricerche di investimento; per questo motivo, questi contenuti devono essere considerati come comunicazioni di marketing in base alle leggi e normative vigenti. Assicurati di avere letto e compreso pienamente la nostra Notifica sulla ricerca di investimento non indipendente e la nostra Informativa sul rischio riguardante le informazioni sopra citate; tali documenti sono consultabili qui.
